1. Field of the Invention
The present invention relates to the structure of an aluminum alloy wheel which can reduce manufacturing costs.
2. Description of Related Art
Japanese Utility Model Laid-Open Sho 62-2401 exemplifies an xe2x80x9cAluminum alloy dowel wheel.xe2x80x9d FIG. 1 of this publication shows the aluminum alloy dowel wheel, in which the dowel plate 5 is sandwiched by the two discs which are bottoms of two deep drawn cups. The outer surfaces of the two cups and dowel plate 5 are welded, and the bolt holes are formed on a flange 4 constituted by the discs of the two cups and dowel plate 5 in order to fixedly attach the wheel to the axle. Thereafter, the bushes 6 are force-fitted into the bolt hole.
In the foregoing publication, the wheel has a three-piece structure, i.e., it is constituted by the two cups and the dowel plate 5. In other words, the wheel includes a plurality of components. In order to force-fit the bush 6 into the bolt hole or weld the two cups and dowel plate 5, these components should be precisely positioned with respect to one another, and the bolt holes on the two cups and dowel plate should be aligned precisely. This means that such a wheel becomes expensive in view of manufacturing and management costs. Furthermore, the bushes are fitted into the bolt holes, which increases the number of components and manufacturing cost of the wheel.
It is therefore an object of the present invention to provide a structure of a wheel which comprises a reduced number of components and is manufactured at a reduced cost.
According to a first aspect of the present invention, a structure of a motor vehicle wheel made of an aluminum alloy includes a rim and a disc, wherein: the wheel is attached to a hub of an axle by engaging bolt holes on the disc with bolts provided on the hub and screwing nuts into the bolts, or by matching the bolt holes on the disc with internal threads provided on the hub, inserting bolts into the bolt holes and screwing the bolts into the internal threads; the disc is made by stamping a single plate; and nut seats or bolt head seats having work hardened layers are provided around the bolt holes.
The disc is made by stamping a single plate in order to reduce the number of components.
The work hardened layers of the nut seats or bolt head seats protect the aluminum alloy wheel against wear when attaching or detaching bolts or nuts.
Therefore, the number of discs is reduced compared with the wheel of the related art. No members are necessary for fastening the disc. Furthermore, no separate nut seats are required, which can reduce the number of components, manufacturing cost and management cost.
The one-piece disc can be manufactured using facilities for steel wheels, which can keep capital investment down.
According to a second aspect of the present invention, the disc is provided with weight reduction holes and ornamental holes.
The wheel becomes light in weight and is of improved external appearance.
According to a third aspect of the present invention, the nut seats or bolt head seats are curved.
Nuts or bolts having conical heads for steel wheels can be used in order to attach the wheel to the hub.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.